1. Field of the Invention
The present invention relates to a method and apparatus for determining a recording condition upon execution of over-writing on an over-write capable magnetooptical disk by a heat shut off method and a pulse train method, and a magnetooptical recording method and apparatus. Over-writing is a procedure for recording new information without erasing previously recorded information. In this case, when recorded information is reproduced, the previously recorded information must not be reproduced. "Over-writing" mentioned in the present specification is a procedure for executing over-writing by simply irradiating a laser beam while pulse-modulating the laser beam according to information to be recorded without modulating the direction and intensity of a bias field Hb.
2. Related Background Art
In recent years, many efforts have been made to develop an optical recording/reproduction method which can satisfy various requirements including high density, large capacity, high access speed, and high recording/reproduction speed, and a recording apparatus, a reproduction apparatus, and a recording medium used therefor.
Of various optical recording/reproduction methods, the magnetooptical recording/reproduction method is most attractive due to its unique advantages in that information can be erased after it is recorded, new information can be recorded, and such an operation can be repetitively performed.
A recording medium used in the magnetooptical recording/reproduction method has a perpendicular magnetic layer or layers as a recording layer. The magnetic layer consists of, for example, amorphous GdFe or GdCo, GdFeCo, TbFe, TbCo, TbFeCo, and the like. The perpendicular magnetic layer normally has concentrical or spiral tracks, and information is recorded on the tracks. There are two types of tracks, i.e., explicit tracks and implicit tracks.